This investigation will further study the efficacy of Silastic #382 as a surgical implant material to inhibit the reformation of osseous bridges subsequent to their resection after partial epiphyseal plate closure. Our primary objective is to further delineate the indications and limitations of this surgical reconstructive procedure for application to children who have sustained partial growth plate closure. This study will determine: 1) the capacity of partial growth plates to maintain longitudinal growth equivalent to its normal contralateral side, 2) the duration of time necessary for silastic retention, 3) the long term effects of silastic retention, 4) the capacity of the epiphyseal plate to expand laterally subsequent to injury and silastic implantation, 5) the amount of growth plate required to maintain effective longitudinal growth, and 6) the biomechanical effects of corrective osteotomies as they relate to effective longitudinal growth of an untethered partial epiphyseal growth plate. Twelve week old puppies will undergo bilaterial operations on their proximal tibias or distal femurs with one extremity serving as a control for the opposite experimental limb. Specific groups have been designed to look at medial, lateral, and central epiphyseal plate defects as they may be affected by osseous bridge resection and silastic implantation. Since the results in animals have been largely the same as those accomplished in a few clinical cases, it is anticipated that the results of this study will establish specific guidelines for the future application of this surgical technique as it may be applied to other injured children. In addition, Silastic #382 may also be useful clinically to inhibit the formation of bone where it is not needed or desired.